She doesn't sound dangerous, especially when everyone from Miley to Madonna seems to drop casual references in songs and in concerts. It may be part of the reason teens are so willing to trust the popular new drug with a girl-next-door name.

Molly, short for "molecule," is a powdered form of MDMA. It's known as "a purer form of Ecstasy," says seventeen-year-old Virginia native Amanda* of the substance's appeal among her friends. "It's supposed to be a clean, happy feeling." And clearly Amanda's friends aren't alone. According to the 2010 National Survey on Drug Use and Health, 12.4 percent of Americans between the ages of eighteen and 25 had experimented with MDMA, and that number is believed to be rising all the time.

But the drug's "clean" reputation is stained with messy consequences. Casey, seventeen, from Texas, recalls a friend having "delusional thoughts on Molly. She felt like she had rats climbing all over her body and called herself an ambulance." Nineteen-year-old Samantha of California remembers the first time her friends experimented, having purchased Molly from "kind of a sketchy person. Everyone who took it was throwing up all night." These girls are three of thousands who have seen the damage Molly can do: Between 2004 and 2009 the Drug Abuse Warning Network tracked a shocking 123 percent increase in the number of emergency room visits involving MDMA.

A triple-digit boost means the drug is becoming more widely and easily available. "It's pretty standard at Coachella," Samantha says of Molly's prevalence in concert culture. "Everyone wants to try it." Just a month before press time, that's exactly what attendees at the Paradiso Festival near Seattle did—and dozens of them were hospitalized, many for suspected overdoses.

Why is the drug so dangerous? It's partly because Molly isn't always so pure. When a 2011 police raid in Syracuse, New York, turned up more than $500,000 worth of the drug, none of it contained MDMA. And in 2012, when Miami police examined 337 samples, more than 80 percent tested positive for a chemical commonly found in the drug bath salts. Anyone who consumed those samples would have discovered that such chemical cocktails—which you never know if you're going to get—could lead to a slew of scary outcomes, like multiple-organ failure and death.'

"My friends think they can't have fun unless they're on Molly," says Tamara, 21, from New York. "The problem is, you can only guess who made it or what it's made from." And when it comes to life or death, guessing just doesn't cut it.